Reflection type color liquid crystal device and method for driving the same using a color filter

Abstract

Reflection type color liquid crystal device, which can display bright and clear colors, is provided. Further, this reflection type liquid crystal device is configured so that a first substrate provided with a transparent electrode, and a second substrate provided with a transparent electrode and a color filter are placed in such a manner as to face each other. Moreover, a pair of polarizing plates are placed at both sides of the substrates thereacross. Furthermore, a reflector plate is provided outside of one of the pair of the polarizing plates. The color filter is composed of filter elements respectively corresponding to the subtractive primaries, namely, yellow, cyan and magenta.

What is claimed is:  
     
       1. A reflection type color liquid crystal device including a liquid crystal cell, the reflection type color liquid crystal device comprising: 
       a first substrate provided with a first transparent electrode,  
       a second substrate provided with a second transparent electrode and a color filter,  
       a liquid crystal layer disposed between the first substrate and the second substrate,  
       a pair of polarizing plates between which said liquid crystal cell is placed, and  
       an optical reflector plate formed outside one of said first substrate and said second substrate,  
       wherein said color filter comprises a yellow filter element, a cyan filter element, and a magenta filter element, and  
       wherein each of the yellow filter element, the cyan filter element and the magenta filter element transmits more than 15% of all wavelength light in the region between 400 nm and 770 nm.  
     
     
       2. The reflection type color display device according to  claim 1 , wherein a lowest transmittance of each of the yellow filter element, the cyan filter element and the magenta filter element is set at a value greater than 20% but no more than 25% in the visible region. 
     
     
       3. The reflection type color liquid crystal device according to  claim 1 , wherein a spectrum representing a transmission characteristic of said yellow filter element intersects with a spectrum representing a transmission characteristic of said magenta filter element at a first point of intersection at a wavelength is approximately 500 nm, 
       wherein a spectrum representing a transmission characteristic of said cyan filter element intersects with said spectrum representing a transmission characteristic of said magenta filter element at a second point of intersection at a wavelength is approximately 600 nm, and  
       wherein the first point of intersection and the second point of intersection are present where the transmittance is more than 30%.  
     
     
       4. The reflection type color liquid crystal device according to  claim 3 , wherein the first point of intersection and the second point of intersection are present where a transmittance is 35% to 60%. 
     
     
       5. The reflection type color liquid crystal device according to  claim 1 , wherein a distance between the optical reflector plate and the color filter is larger than dot pitches. 
     
     
       6. The reflection type color liquid crystal device according to  claim 5 , wherein the distance between the optical reflector plate and the color filter is twice to three times each of the dot pitches. 
     
     
       7. The reflection type color liquid crystal device according to  claim 1 , further comprising pixel electrodes placed on one of said first substrate and said second substrate in a matrix, and 
       a switching element connected to said pixel electrodes.  
     
     
       8. A color liquid crystal device including a liquid crystal cell, the color liquid crystal device comprising: 
       a first substrate provided with a reflector,  
       a second substrate,  
       a liquid crystal layer disposed between the first substrate and the second substrate, and  
       a color filter positioned between the first substrate and the second substrate,  
       wherein said color filter comprises a yellow filter element, a cyan filter element, and a magenta filter element, and  
       wherein each of the yellow filter element, the cyan filter element and the magenta filter element transmits more than 15% of all wavelength light in the region between 400 nm and 770 nm.  
     
     
       9. The color liquid crystal device according to  claim 8 , wherein an optical diffusion plate is placed between the second substrate and a polarizing plate. 
     
     
       10. The color liquid crystal device according to  claim 8 , wherein a lowest transmittance is 20% or more in the visible region. 
     
     
       11. The color liquid crystal device according to  claim 10 , wherein the lowest transmittance is 30% or more in the visible region. 
     
     
       12. The color liquid crystal device according to  claim 8 , wherein a spectrum representing a transmission characteristic of said yellow filter element intersects with a spectrum representing a transmission characteristic of said magenta filter element at a first point of intersection at a wavelength is approximately 500 nm, 
       wherein a spectrum representing a transmission characteristic of said cyan filter element intersect with said spectrum representing a transmission characteristic of said magenta filter element at a second point of intersection at a wavelength is approximately 600 nm, and  
       wherein the first point of intersection and the second point of intersection are present where a transmittance is more than 30%.  
     
     
       13. The color liquid crystal device according to  claim 12 , wherein the first point of intersection and the second point of intersection are present where the transmittance is 35% to 60%. 
     
     
       14. The color liquid crystal device according to  claim 8 , further comprising: 
       an optical reflector plate formed outside one of the first and second substrates,  
       wherein a distance between the optical reflector plate and the color filter is larger than dot pitches.  
     
     
       15. The color liquid crystal device according to  claim 14 , wherein the distance between the optical reflector plate and the color filter is twice to three times each of the dot pitches. 
     
     
       16. The color liquid crystal device according to  claim 8 , further comprising pixel electrodes placed on one of said first substrate and said second substrate in a matrix, and 
       switching elements connected to said pixel electrodes.  
     
     
       17. An electronic device comprising said reflection type color liquid crystal device according to  claim 1 . 
     
     
       18. An electronic device comprising said color liquid crystal device according to  claim 8 .